Weakish tell-tale stream. help?

[davejohnson]

New to outboards, so please humor a newbie question.<br />The other day, on a quick run to test a rebuilt fuel pump, I noticed that the stream of water from the tell-tale hole of my '78 Mercury 900 inline 6 isn't as straight-out strong as it has been; more like an erratic spurting, and included some puffs of steam along with it. Also, I think it takes a bit longer than normal to start coming out, like perhaps 45 seconds. Are you experts of the school of thought that 'any water is good water' from the pee hole, or should it be a strong, steady stream? And what's the rule of thumb for the time it takes to start streaming? I don't know the condition of the water pump, as I just got the thing this summer.<br />Your thoughts please? Thank you.<br />P.S...is a lower-unit drop something a shadetree pickup truck mechanic could do? Need any special tools? Thank you.

 

[andrewkafp]

Re: Weakish tell-tale stream. help?

If you have noticed a change, That's the time to renew the impeller. Puffs of steam mean lack of water flow.If your boat has a pressure gauge, it should be pumping about 1 -2 psi at idle and over 10psi at high revs. The waterpump change is reasonably easy. A manual is recomended along with posting here regularly for step by step instructions from members with a similar motor.<br />This may interest you.<br />www.myfishingpictures.com<br />Search by member Hoo's yur Daddy. He has 20 odd sequentials of an impeller change on a Yammie (nearly the same).<br />This is the type of pic

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[JasonJ]

Re: Weakish tell-tale stream. help?

It sould be a steady stream. Inlines don't have super strong streams, but it should be continuous. You may want too check for debris in the inlets, but it sounds like the impeller is at the end of its usefull existence. It has probably either taken a set or has lost a few blades.

 

[outboard tech]

Re: Weakish tell-tale stream. help?

If you're seeing steam, it's time for a pump assembly. (not just an impeller)The most common mistake on the "old stlye" high pressure mercury pump is putting new impellers in worn out housings, and re-using scored wear plates and blown out gaskets. (Come on guys, you're already in there, don't slap worn out parts back into your cooling system.) This is a managable job for the average shade tree; don't forget to lube the driveshaft and shift shaft splines when re-installing.

 

[phatmanmike]

Re: Weakish tell-tale stream. help?

When you own a big Merc, No-one can say you have a small Johnson

but i do, i have 2 small johnsons

 

[andrewkafp]

Re: Weakish tell-tale stream. help?

Phatmanmike...<br /><br />Size doesn't matter.

 

[E120B]

Re: Weakish tell-tale stream. help?

it's all about if they keep asking for it

 

[agrazela]

Re: Weakish tell-tale stream. help?

Davejohnson,<br /><br />Check to be sure the water outlet tube (or it's fittings) snaking from top of the head to the pee-hole isn't cracked/leaking. Mine did this once and the symptoms were like what you described, as water dribbled down the outside of the block inside the cowling creating a poor pee-stream and some steaming.

 

[ronmold]

Re: Weakish tell-tale stream. help?

Have the prostate checked!

 

[phatmanmike]

Re: Weakish tell-tale stream. help?

back to the subject.....<br /><br />my merc 1150, 1976 by the way.... had similar symptoms. youll def need to check water pump. do the WHOLE KIT !! don t be a cheep a$$ and get just the impeller.<br /><br />waht mine did was run fine at idle, but the after that, steam and dribbles would come out the pee hole. i removed the cylinder head cover and found handfullls of sand impeeding the water flow. i have since removed the sand and now motor pees like a lil girl after too much mountain dew